i have not read mccains book, but according to paul Abrams on huffington post, John mccain admitted in his own book that he was running for office only out of personal ambition:

"McCain has written ("Worth Fighting For") and recorded it in his own voice, that he runs for President not to accomplish reforms or even for patriotism, but because it is his personal ambition."

The ad begins with a shot of the White House with the flag half mast.
"Nine vice presidents have had the responsibility of assuming the presidency in times of national turmoil."
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A photo of Barack Obama thinking at his desk pans across.
"Barack Obama understands how important it is to chose someone who could assume that mantel."
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Create an ad that says "The Bush-McCain policies are not failed policies - they are policies that did exactly what they were designed to do - and that is to push big oil to record profits and to give tax cuts to the rich while the middle class continues to suffer. These are not failed policies, heck, even John McCain says the fundamentals of the economy are strong."

As you know, John McCain is pressuring Obama to go to Iraq. The RNC has even posted a clock on their website telling us how many days it's been since Obama went to Iraq. Currently, the number is 871.
How to Respond?
First, Obama should say that this isn't about how many Washington politicians go to Iraq. This is about how many American soldiers come home from Iraq.